A widely used prior known dolly has a roller assembly having a caterpillar type tread comprising a plurality of small-diameter, steel rollers connected at their ends by a chain to form a continuous belt. Such dollies are able to move very heavy weights, but are easily stopped by small surface irregularities. For example, when the dolly is carrying a heavy load, an object as thin as a dime may stop forward movement. Forward movement may also be stopped by an abrupt upward change in the plane of travel of the dolly. When such an uneven surface or incline is encountered, the entire load being carried by the dolly is shifted to those roller(s) still in contact with the surface over which the load is being moved. Those rollers still in contact with the surface must be able to support the weight of the entire load being carried by the dolly, necessitating the use of larger rollers. Additionally, due to the small diameter of the rollers commonly employed in dollies, small irregularities in the surface over which the dolly is passing will have a magnified effect upon the amount of energy required to move the loaded dolly over the irregular area or inclined surface. To overcome these problems, a larger dolly may be used and/or a greatly increased force may be applied to moving the load. It is apparent that neither of these solutions is economically attractive. Additionally, it may prove to be difficult to switch dollies during transit with a load, especially when the load is fragile and easily damaged by the additional handling required. In other circumstances, the application of a greater force to move the load may not be feasible due to the unavailability of the additional power.
A second problem encountered in known equipment-moving dollies results from the use of steel wheels or rollers in their construction. This causes two problems. First, the steel rollers may be very injurious to the surface over which they travel, especially to tiled surfaces commonly encountered in office buildings and the like. A second problem with steel wheels is their ability to transmit the unevenness of the floor to the equipment in the form of shock waves which may not be tolerated by sensitive equipment, such as electronic equipment, computers and the like.
The present invention relates to an improved equipment-moving dolly which equalizes the weight of the load over all of the rollers of the carriage base.
A separate embodiment is the means for immobilizing the weight-equalizing means.
Another embodiment of the invention is the use of elastomeric rollers to reduce damage to sensitive substrates such as tile floors as well as minimize the transmission of shock waves through the rollers.